Process for the preparation of a silica-metal oxide hydrogel catalyst



June 14, 1949. I E. A. HUNTER EI'AL 2,472,831

PROCESS FOR THE PREPARATION OF A SILICA-METAL OXIDE HYDROGEL CATALYST Filed Feb. 28. 1947 ddDJ m O 02 j 'drc l ark/eaters I M- Clbborne' Patented June 14, 1949 SILICA-METAL OXIDE LYST RYDROGEL CATA- Edward A. Hunter and Charles N. Kimberlin, Jr., Baton Rouge, La., assignors to Standard Oil Development Company, a corporation of Delaware (Application February 28, 1947, Serial No. 731.562

11 Claims.

Our invention is concerned with improved cat- 7 alysts, and more specifically relates to an improved process for the preparation of catalysts suitable for utilization in cracking, reforming, isomerization, polymerization, alkylation and similar treating processes. Our invention is particularly concerned with an improved method for the preparation of catalyst comprising silica. In accordance with our invention, catalysts compising silica are prepared by treating a silica-magnesia hydrogel with a metal salt solution under conditions to produce a catalyst comprising silica and the oxide'of the metal.

It is well known in the art to improve the quality of oils, particularly petroleum oils, by treating the same with catalyst under various operating conditions. For example, it is known to treat high-boiling petroleum oils with a catalyst comprising silica at temperatures in the range from about 600 F. to about 1100 F. in order to crackthe oil and to secure petroleum oil fractions boiling in the motor fuel boiling range. Oxides of other metals, as for example, magnesium, manganese, zirconium, beryllium and aluminum are employed in conjunction with the silica. Particularly desirable catalysts suitable for treating petroleum oils boiling in the gas-oil boiling range in order to produce lower boiling fractions comprise silicaberyllium, silica-uranium and silica-manganese. Suitable hydrogenation and dehydrogenation catalysts comprise silica-zinc and silica-chromium.

Thesecatalysts have been prepared by various procedures. One method employed is to prepare the silica, hydrogel by mixing an alkali silicate with an acid. The alkali silicate usually comprises a sodium silicate (Na2O.3.25SiOz) solution having a. specific gravity of about 1.2. This is mixed with a sulfuric acid having a specific gravity somewhere in the range of about 1.19. The

hydrosol may be impregnated with a soluble salt of the desired metal or the hydrosol may be allowed to gel and the resulting hydrogel washed and. soaked in a solution comprising the salt of the desired metal or metals.

One method employed for the preparation of a silica magnesia catalyst is to prepare the hydrogel by the mixing of a silicate and sulfuric acid. The hydrogel is washed and mixed and granulated with magnesia and water. The mixture is passed through a colloid mill and homogenized. The catalyst is aged at room temperature for a period from about 24 to 72 hours. Elevated temperatures have also been employed in which cases, the aging time period is reduced to a period of from about 5 to hours. The catalyst is dried 2 at a temperature in the range from about 200 F. to 270 F. Another method utilized for the preparation of the silica-magnesia catalyst is to prepare the silica hydrogel by mixing sulfuric acid and an alkali metal silicate. The silica hydrogel is washed and impregnated with magnesium sulfate. The impregnated silica hydrogel is treated with an ammonia solution to precipitate the magnesia. This may require a time period of from about 8 to 24 hours. A preferred method of preparing a catalyst comprising silica and magnesia is to add magnesia to a silica hydrosol or to a silica hydrosol impregnated with a metal salt such as with an aluminum salt. The mixture is washed preferably at elevated temperatures. The general process comprises adding magnesia preferably as a slurry in water to a silica hydrosol which has been impregnated with a salt, as for example, with an aluminum salt. The action of magnesia is to neutralize the free acid, thus causing rapid setting of the hydrosol to the hydrogel and also to decompose the aluminum salt or other salt present causing precipitation of alumina within and throughout the gel. Excess magnesia used over these requirements remains in the finished product as magnesia. The magnesia employed to neutralize the acid and the salt of the added third metal, reacts to form magnesium salt which is removed upon washing. If it is desired to produce a gel comprising silica and magnesia, excess magnesia is added preferably as a water slurry over that required to neutralize the excess acidity thus causing the formation of a gel comprising silica and magnesia. r I

We have now discovered an improved process for the preparation of a catalyst gel comprising silcia and a metal oxide the metal of which is preferably selected from groups 2, 6 and 7 of the periodic table. .Our process comprises preparing a hydrogel of silica and magnesia. This is prepared by any suitable means, preferably by preparing a silica hydrosol by the mixing of a sodium silicate with an acid preferably sulfuric acid. The silica hydrosol is treated with magnesiapreferably with a water slurry of magnesia through a jet spray nozzle and gelled to form a gel comprising silica and magnesia. The resulting gel is treated with a solution of a metal salt the metal of which is preferably selected from groups 2, 6 and 7 of the periodic table to produce a gel catalyst comprising silica and a metal oxide.

The process of our invention may bereadily understood by reference to the drawing illustrating an embodiment of the same.

Referring specifically to the drawing a silica sol is prepared by withdrawing sulfuric acid from zone I. by means of line I and mixing the acid with sodium silicate which is withdrawn from zone II by means of line I. The mixtures pass through line I. A water slurry of magnesia is withdrawn from zone 30 and introduced into line 3 by means of line 4. The mixture is passed through a spray nozzle arrangement 40. Nozzle arrangement 40 may comprise a rotating or equivalent spray means. The material passing from means ll comprises a silica-magnesia sol which rapidly sets to a silica-magnesia gel. The gel particles fall downwardly through zone 50 which preferably comprises air. It is to be understood however that zone in may contain oil or another water immiscible fluid.

In accordance with our invention a metal salt solution is withdrawn from zone 60 and introduced in the bottom of zone 50 by pumping or equivalent means 5. For the purpose of illustration it is assumed that the metal salt solution comprises a metal sulfate solution. In the bottom of zone 50 the magnesia of the gel is replaced by the metal oxide of the metal salt resulting in a gel comprising silica and the metal oxide.

The solution is withdrawnfrom zone 50 by means of line 8 and passed through a separation and washingzone 10. The filtrate comprising a metal sulfate solution is withdrawn from zone II by means of line I and is preferably recycled by means of line 9. This solution however may be partially or wholly withdrawn from the system by means of line II in order to eliminate magnesium and sodium sulfates. The solids after removal of the filtrate comprise gel particles consisting of silica and metal oxide. The

solids also comprise magnesium and sodium sulfates. The magnesium and sodium sulfates are removed by washing'the solids with water which is introduced into zone I0 by means of line I. The water containing dissolved'magnesium and uranium sulfates may be utilized and a double replacement secured.

, The process may be somewhat modified, for example, the silicahydrogel may be washed with water to remove magnesium sulfate and sodium sulfate prior to soakingthe silica-magnesia hydrogel in the metal salt solution. Although we prefer to use room temperatures, in the soaking operation it is to be also understood that elevated temperatures and higher pressures may be employed.

By preparing the silica metal oxide hydrogel in accordance with our process, it is possible to get a hydrogel comprising a relatively high percentage of the metal oxide.

The process of our invention is not to be limited by any theory as to mode of operation but only in and by the following claims in which it is desired to claim all novelty insofar as the prior art permits.

We claim:

1. Improved process for the preparation of a hydrogel comprising silica and an oxide of a metal, other than magnesium, selected from groups 2, B and 'I of the periodic table which comprises admixing a silica sol and an aqueous slurry of magnesia, converting the resulting mixture to a silica-magnesia hydrogel, contacting said hydrogel with a solution of a salt of a metal, other than magnesium, selected from groups 2, 6 and 7 oftheperiodic table for a sumcient period of time to permit the magnesia of the hydrogel to react with the said metal salt to form a silicametal oxide hydrogel and a magnesium salt, and washing the silica-metal oxide hydrogel free of the magnesium salt.

2. Process as defined by claim 1 wherein said metal salt solution is a sulfate solution.

3. Improved-process for the preparation of a hydrogel comprising silica and an oxide of a Q metal, other than magnesium, selected from sodium sulfates is removed from zone I0 by means of line I. I

The washed silica gel comprising silica and metal oxide is withdrawn from zone 10 by means of line I: and passed into a drying zone 80. Here the gel is dried or heat treated at the desired temperature for any desirable period of time. The dried or heat treated gel is withdrawn from zone 80 and passed to storage zone 90 and handied in any manner desirable.

Our invention broadly covers a method of producing hydrogels comprising silica and a metal oxide other than magnesia. In accordance with our process our gels are preferably prepared by spraying a silica magnesia hydrogel into a metal salt solution. The metal of the salt may be any metal selected from groups 2, 3, 4, 6, 7 and 8 of the periodic table. Suitable metals are, for example, beryllium, zinc, aluminum, titanium, zirconium, thorium, chromium, uranium, manganese iron, cobalt and nickel.

Any salt of the above metals may be used which is characterized by the fact that the salt will decompose so that the metal of the salt will form the oxide and replace the magnesia in the silica-magnesia, hydrogel. Satisfactory salts of the above material are, for example, the sulfates, the chlorides and the nitrates.

In general the preferred salt comprises the sulfate. It is to be understood that mixed salts such as beryllium sulfate and chloride may be used. Also mixed salts such as beryllium and groups 2 6 and 7 of the periodic table which comprises spraying a mixture of a silica sol and an aqueous slurry of magnesia into a zone wherein the sprayed mixture is converted to particles of silica-magnesia hydrogel, contacting the said hydrogel particles in said zone with a solution'of a salt of a metal, other than magnesium, se-

lected from groups 2, 6 and 7 of the periodic table for'a sufficient period of time to cause the magnesia of the silica-magnesia hydrogel to react with the metal salt to form a hydrogel of silica and of the oxide of the metal selected, and a magnesium salt, and washing the silica-metal oxide hydrogel free of the magnesium salt.

4. Process as defined by claim 3 wherein the metal of said metal salt solution is a group 2 metal.

5. Process as defined by claim 3 wherein the metal of said metal salt solution is a group 6 metal.

6. Process as defined by claim 3 wherein the metal of said metal salt solution is a group '7 metal.

"1. Improved process for the preparation of a hydrogel comprising silica and an oxide of a metal, other than magnesium. selected from groups 2, 6 and 7 of the periodic table which comprises preparing a silica-magnesia hydrogel, soaking said hydrogel in a solution of a salt of a metal, other than magnesium, selected from groups 2, 6 and 'l of the periodic table, permitting said hydrogel to remain in contact with the metal'salt solution for a sufficient period of time Is to cause the magnesia of the hydrogel to react 5 with the metal salt to form a silica-metal oxide hydrogel and a magnesium salt and washing the silitca-metal oxide hydrogel tree of magnesium sal w 8. Improved process for the preparation of a hydrogel comprising silica and an oxide of a metal other than magnesium, selebted from groups 2, 6 and 7 of the periodic table which comprises spraying a mixture of a silica sol and an aqueous slurry of magnesia into an initial zone wherein the sprayed mixture is converted to particles oi silica-magnesia hydrogel, contacting said hydrogel particles in a portion of said zone with a solution of the salt of a metal, other than magnesium, selected from groups 2, 6 and 7 of the periodic table for a sufiicient period of time to cause the magnesia of the hydrogel to react with the metal salt to iorm a magnesium salt and a silica-metal oxide hydrogel, withdrawing the resulting mixture of silica-metal oxide hy'drogel, metal salt solution and magnesium salt from said initial zone and passing the'same to a second zone, separating the solids from the mixture by filtration in said second zone, recycling the resulting filtrate to said initial zone.

washing the separated solids in said second zone -metal of said metal salt anassi with water to dissolve out magnesium salt from the solids, removing the washed silica-metal oxide hydrogel from said second zone and passing said washed hydrogel to a. drying zone and recovering dried hydrogel from said drying zone.

9. Process as defined by claim 8 wherein the metal of said metal salt solution is a group 2 metal.

10. Process as defined by claim 8 wherein the metal of said metal salt solution is a group 6 metal.

11. Process as defined by claim 8, wherein the solution is a group 7 metal.

EDWARD A. HUN'IER; CHARLES N.,KIMBERLIN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Bates May 19, 1942 

